I have tried back, front and all fours when chaining up a 4x4. Of course chaining all 4 wheels is the best, but I don't even own enough chains of the correct size to do that on my truck now. Regarding chaining-up the front versus the back, in my opinion it depends on the conditions.
For deep fresh snow, unplowed roads, or cold road-packed snow your main concern is not getting stuck. Chains on the front will pull you through most anything, and your rear wheels will tend to follow in the tracks of the front wheels. Chain the fronts.
For black glare ice, freezing rain, and wet icy road pack your main concern is staying on the road and being able to stop. Chains on the rear will keep the back of the truck where it should be. Slow down before any corners, then pray and turn the wheel keeping a good "feel" of the wheel and straghten your turn if you feel the front tires starting to slide. Good radials with tread and siping should steer you fine if speed is OK. Chain the rears.
Just my opinion. Main thing to remember is that 4x4 trucks will slide off the road just as easily as any other vehicle, and they will make a bigger hole in the snow bank when they land. Take it easy and arrive alive.
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Just got my 2001 2500 QC, SB, 4x4, ETH 6-sp, 3. 54 LSD, SLT++ (everything but those lights on top of the roof), White over Silver, Tan leather. Picked it up 8/31/00.